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Description
An annual growing up to 90 cm high. Culms many-noded, few.
Leaf- sheath tight. Leaf-blade linear, long-pointed. Upper glume always
distinctly emarginate or two-fid at the summit and with a very distinct
mucro or short awn between the acute or obtuse lobes. Awns scabrous, about
1.5 cm long (Andrews, 1956). The culms are yellow to bright green, curing
to a straw colour. The seed- heads may be purple.
Season of growth
Summer, but can grow out of season if temperature and moisture
are suitable.
Altitude range
Sea-level to 2 250 m. It is dominant in Zimbabwe at altitudes
below 600 m.
Rainfall requirements
It is dominant in Zimbabwe in a rainfall regime of 300380 mm
falling mainly between November and March. It requires a rainfall in excess
of 250 mm.
Drought tolerance
Being an annual, it usually escapes drought once it has had
sufficient rain to germinate.
Soil requirements
It prefers sandy soils but has a wide tolerance.
Land preparation for establishment
It will establish on roughly prepared ground and can be oversown
into unprepared land.
Sowing methods
Broadcast the seed on to the surface and, where possible, cover
lightly.
Main attributes
A common pioneering species on disturbed soil, waste land,
rocky places and fallows.
Main deficiencies
Its short life and severe decline in nutritive value soon after
it dries.
Palatability
It is a late-flowering, unpalatable annual in the United Republic
of Tanzania (Wigg, Owen & Makurasi, 1973). The sharp seeds and stiff
awns repel animals when mature. It provides an abundance of feed for a
short time in Arizona.
Chemical analysis and
digestibility
Göhl (1975) has listed its chemical analysis in Table
15.4.
Genetics and reproduction
2n=22 (Fedorov, 1974).
Seed production and harvesting
It will grow and set seed at any time of the year in Arizona
when moisture and temperature are favourable, but is predominantly summer-growing.
Economics
It is one of the better annual grasses in Arizona ranges, but
provides poorer forage than most perennials.
Animal production
It is used for semi-arid cattle ranching in Zimbabwe. At Tuli
station in southern Zimbabwe, the natural veld was estimated by Rattray
(1962) to carry one animal per ten hectares. When the carrying capacity
was increased to one animal per eight hectares an almost pure stand of
Aristida adscensionis was induced, which is unpalatable and provides little
ground cover during the dry season.
Further reading
Humphrey, 1960a.
Value for erosion control
It easily colonizes bare ground.
Natural habitat and distribution
Occurs in any disturbed poor soils in grassland and open bush
throughout tropical Africa. Introduced to the United States.
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